Recently, LTE-Advanced has been standardized as an advanced variation of LTE (Long_Term_Evolution), which was standardized in 3GPP Releases 8 and 9. The LTE-Advanced specifications include a carrier aggregation technique. Carrier aggregation is a technique of using aggregated carrier waves of blocked bands each having, for example, a bandwidth of 20 MHz for simultaneous transmission and reception, and each carrier wave is called a component carrier. There are two types of carrier aggregation: Intra-band carrier aggregation uses aggregated component carriers in the same frequency band for transmission and reception; and inter-band carrier aggregation uses aggregated component carriers of different frequency bands for transmission and reception. Two formats of inter-band carrier aggregation are inter-band contiguous carrier aggregation, which selects the component carriers from contiguous frequency bands, and inter-band non-contiguous carrier aggregation, which selects the component carriers from non-contiguous frequency bands.
FIG. 1 is a block diagram showing the configuration of a conventional wireless circuit 900 that enables transmission and reception across multiple bands (three frequency bands). As shown in FIG. 1, the wireless circuit 900 includes a transmission-reception antenna 911; a reception antenna 912; a single-pole three-throw switch 921 having a common contact connected to the transmission-reception antenna 911; a single-pole three-throw switch 922 having a common contact connected to the reception antenna 912; duplexers 931, 932, and 933 which have respective common contacts connected to transfer contacts of the switch 921 and receive transmission and reception signals in first, second, and third frequency bands, respectively; band-pass filters 941, 942, and 943 which are connected respectively to transfer contacts of the switch 922 and receive reception signals in the first, second and third frequency bands; amplifiers 951, 952, and 953 which are connected to transmission terminals of the duplexers 931, 932, and 933 and amplify the transmission signals in the first, second, and third frequency bands; low-noise amplifiers 961, 962, and 963 which are connected to reception terminals of the duplexers 931, 932, and 933 and amplify the reception signals in the first, second, and third frequency bands; low-noise amplifiers 964, 965, and 966 which are connected to output terminals of the band-pass filters 941, 942, and 943 and amplify the reception signals in the first, second, and third frequency bands; band-pass filters 971, 972, 973, 974, 975, and 976 which are connected to output terminals of the low-noise amplifiers 961, 962, 963, 964, 965, and 966, respectively, and filter the reception signals; and an RFIC 980 which has transmission ports Tx1, Tx2, and Tx3 for the first, second, and third frequency bands, first reception ports (1)Rx1, (1)Rx2, and (1)Rx3 for the first, second, and third frequency bands, and second reception ports (2)Rx1, (2)Rx2, and (2)Rx3 for the first, second, and third frequency bands. The RFIC here is an integrated circuit that includes most parts of a high-frequency analog transmission and reception circuit and its control circuit, required in portable terminals, except for duplexers, transmission amplifiers, and low-noise amplifiers. Some RFICs include low-noise amplifiers, but the amplifiers are provided outside the RFIC in the present configuration example. As shown in FIG. 1, to send and receive carrier waves in different frequency bands, the numbers of duplexers, amplifiers, and band-pass filters should correspond to the number of frequency bands, making the circuit complex, increasing the circuit footprint, and making it difficult to reduce the size of the portable terminals. The increased circuit footprint also increases the packaging cost.
On the other hand, a wireless communication circuit disclosed in Patent literature 1 simplifies the circuit configuration and reduces the circuit footprint by using a broadband power amplifier that can be utilized for transmission signals in multiple frequency bands. The wireless communication circuit in Patent literature 1 improves the simplicity of the circuit by limiting the transmission outputs of the RFIC to one or two (high-band and low-band outputs) and having the broadband power amplifier and an input-output matching correction circuit.